Utility of nodal basin staging ultrasound in early-stage breast cancer

Background: Nodal basin staging ultrasound can guide treatment decisions for early-stage breast cancer (BC) patients, yet there is a lack of consensus for its utility in this patient population. Our program implemented a routine nodal basin staging ultrasound protocol for all newly diagnosed BC patients in 2013. In this study, we aimed to determine the impact of this protocol on rates of neoadjuvant chemotherapy (NAC), axillary radiation, and axillary lymph node dissection (ALND), time to surgery (TTS) as well as staging for early-stage BC patients. Methods: We performed a retrospective review of patients with clinical stage I and II BC from 2009–2012 and 2015–2018. The pre-intervention group included patients in 2009–2012 who did not undergo routine nodal basin ultrasound whereas the post-intervention group included patients in 2015–2018 who did undergo routine nodal basin ultrasound. Nodal basin ultrasound was conducted by our proficient breast radiologists adhering the MD Anderson protocol, progressively scanning from the axilla to other nodal basins as deemed necessary. The Phillips epiq 5 ultrasound machine, equipped with a 12-5 linear probe was utilized for this purpose. We then compared TTS, rates of NAC, axillary radiation, and ALND and pathologic staging between the two groups. Chi square and Mann Whitney U tests were used for the statistical analysis. Results: There were 586 patients in the pre-intervention group and 1,232 patients in the post-intervention group. There was no significant difference in clinical stage between the two groups (P=0.18). The post-intervention group had longer TTS (54 vs. 48 days, P=0.004), as well as a higher rate of NAC (48.0% vs. 27.3%, P<0.001) and a lower rate of ALND (16.6% vs. 25.6%, P<0.001) and a larger proportion of patients diagnosed with pathologic early-stage disease (69.5% vs. 61.3%, P<0.001). There was no significant difference in the rate of axillary radiation between the two groups. Conclusions: Our study demonstrated longer time period to surgery and higher rates of NAC, but lower rates of axillary dissection and potential downstaging for those patients after our adoption of nodal staging ultrasound for early-stage invasive BC. The routine use of nodal basin ultrasound is an important tool in treatment decisions for early-stage BC.